Aging has been shown to be one of the risk factors for the development of vitamin D deficiency. It is also generally known that ageing is a key risk factor for cognitive decline and dementia. Mice lacking vitamin D receptors (VDRs) demonstrate an increased anxiety level, inferior nest building, and impaired motor performance, which suggests a role for vitamin D in various brain processes. Mechanistically, there appears to be an effect of vitamin D on intraneuronal calcium regulation and the synthesis and degradation of several neurotransmitters and neurotrophins. Further, Vitamin D has been suggested to beneficially affect amyloid 13 phagocytosis and clearance by macrophages
Although a recent review by Eyles et al. 2012 Front. Neuroendocrinol. (http://dx.doi.org/10.1016/j.yfrne.2012.07.001) showed that a role for vitamin D in certain brain functions is confirmed by neurobiological evidence, they also concluded that there is still insufficient and inconsistent data from epidemiological studies and well-designed randomized controlled trials in humans to verify this.
Several human population based studies investigated the possible role of 25-OH D3 in cognitive performance, although none of these describe intervention trials involving 25-OH D3:
Annweiler et al 2009 Eur J Neurol 16(10):1083-1089 looked at the literature for studies showing a significant positive correlation between 25-OH D3 levels and cognitive performance. The results were inconsistent.
Breitling et al 2012 Experimental Gerontology 47(1):122-127 found that low vitamin D levels are associated with worse cognitive function in the elderly assessed after 5 years. High levels of vitamin D showed a plateau of cognitive performance functioning.
Data from Brouwer-Brolsma et al 23 Jun. 3, 2012 Eur J. Nutr. online publication DOI 10.1007/s00394-012-0399-0 did not support the hypothesis that higher 25-OH D3 levels were associated with better cognitive functioning. There was no information reported specifically on executive functioning.
Chan et al. J Affect Disord. April 2011; 130(1-2):251-259. Serum levels of 25-OH D3 were found to be inversely associated with depression. However, no association was found between 25-OH D3 levels and cognitive impairment. Specific effects on executive functioning were not reported.
Seamans et al 2010 Eur. J Clin Nutr. 4(10):1172-1178 looked at associations between serum 25-OH D3 status and various aspects of cognitive function. There was an association between 25-OH D3 levels in some aspects of spatial working memory, but not all such aspects.
Lee et al 2009. J Neurol Neurosurg Psychiatry 80(7):722-729 found that lower scores on the Digital Symbol Substitution Test were associated with lower 25 OH D3 levels, but this correlation was not seen for other cognitive tests.
WO 1995/02409 (Trustees of the Univ of Kentucky) disclose use of vitamin D, its metabolites and precursors to protect against neuron loss, such as is observed in Alzheimers and other neuronal based diseases.
It would be desirable to provide a safe, effective way to enhance or retain cognitive executive functioning in healthy people.